Mandrels and mandrel balls help prevent tube buckling, wrinkling, and collapse in a rotary-draw bending operation. During bending, high normal forces between the mandrel and an inner surface of the tube create frictional forces at the contact interface. The relative motion between the outer surfaces of the mandrel and inner surface of the tube (workpiece) often creates galling on the inner surface of the tube. The presence of galling creates the need for cleaning (down-time, loss of productivity, etc.) and often leads to failure of the workpiece.